High-Power Large-Aperture Bottom-Emitting 980-nm VCSELs With Integrated GaAs Microlens

Microlens-integrated bottom-emitting 980-nm vertical-cavity surface-emitting lasers (VCSELs) with an emitting window aperture of 400 mum have been fabricated. A novel material structure with nine InGaAs-GaAsP quantum wells and slightly decreased reflectivity of n-type distributed Bragg reflectors (n-DBRs) are employed to increase the output power. A convex microlens is fabricated by a one-step diffusion-limited wet-etching technique on the GaAs substrate. The diameter of the active layer is about 200 mum after lateral oxidation, and the nominal diameter of the microlens is 400 mum. The maximum output power is 200 mW at continuous-wave operation at room temperature. The far-field divergence angles thetas
_||
and thetas
_perp
of the single device at a current of 4A are 8.7deg and 8.4deg, respectively. The optical beam performance between the microlens-integrated VCSEL and ordinary VCSEL is compared.